Frank Zappa's Mothers Of Invention madcap sidekick Jim 'MOTORHEAD' SHERWOOD has died, aged 69.The classically-trained multi-instrumentalist and vocalist passed away on Christmas Day (25Dec11), according to RollingStone.com. Sherwood was a longtime friend of Zappa's, who appeared on the zany rocker's albums Freak Out!, Cruising with Ruben & the Jets and Lumpy Gravy. He also starred in Zappa's 1971 film 200 Motels.